From ffdb88a79c57a8a527378e6dc6919425a0318520 Mon Sep 17 00:00:00 2001
From: Aly Raffauf <aly@aly.codes>
Date: Sun, 16 Aug 2026 09:11:46 -0400
Subject: [PATCH] perf(nix): share package sets across evaluations

---
 flake.nix                     | 29 ++++++++++++++++++++++++++---
 nix/modules/nixos/nixpkgs.nix |  9 +++------
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/flake.nix b/flake.nix
index 7a03dbc3..60618d2b 100644
--- a/flake.nix
+++ b/flake.nix
@@ -64,9 +64,32 @@
     ];
   };
 
-  outputs = inputs @ {flake-parts, ...}:
-    flake-parts.lib.mkFlake {inherit inputs;} {
-      systems = ["aarch64-darwin" "x86_64-linux"];
+  outputs = inputs @ {
+    flake-parts,
+    nixpkgs,
+    ...
+  }: let
+    sharedPackageSets = {
+      aarch64-darwin = import nixpkgs {
+        system = "aarch64-darwin";
+      };
+
+      x86_64-linux = import nixpkgs {
+        system = "x86_64-linux";
+        config.allowUnfree = true;
+        overlays = [inputs.self.overlays.default];
+      };
+    };
+  in
+    flake-parts.lib.mkFlake {
+      inherit inputs;
+      specialArgs = {inherit sharedPackageSets;};
+    } {
+      systems = builtins.attrNames sharedPackageSets;
+
+      perSystem = {system, ...}: {
+        _module.args.pkgs = sharedPackageSets.${system};
+      };
 
       imports = [
         (inputs.import-tree ./nix/modules)
diff --git a/nix/modules/nixos/nixpkgs.nix b/nix/modules/nixos/nixpkgs.nix
index 484fe4d5..682336c6 100644
--- a/nix/modules/nixos/nixpkgs.nix
+++ b/nix/modules/nixos/nixpkgs.nix
@@ -1,8 +1,5 @@
-_: {
-  flake.nixosModules.default = {self, ...}: {
-    nixpkgs = {
-      config.allowUnfree = true;
-      overlays = [self.overlays.default];
-    };
+{sharedPackageSets, ...}: {
+  flake.nixosModules.default = {
+    nixpkgs.pkgs = sharedPackageSets.x86_64-linux;
   };
 }
-- 
2.51.2